In incremental type linear encoder devices, reference marks are provided to detect reference positions such as the origin. The linear encoder devices detect the reference positions based on reference signals output when sensors detect the reference marks and phase signal (Z signals) output according to information detected by the sensors from scales.
Since the reference positions are detected based on combinations of signal levels of the reference signals and the phase signals, it is necessary to adjust positions at which the reference marks are attached so that the reference signals can be obtained at predetermined position (for example, Non Patent Literature 1). There are also linear encoder devices designed to detect reference positions by correcting reference signals output when sensors detect reference marks, instead of adjusting positions at which the reference marks are attached.